1. Field of the Invention
This invention relates to a radiation image read-out method and apparatus, wherein stimulating rays are irradiated to a stimulable phosphor sheet, on which a radiation image has been stored, and light, which is emitted by the stimulable phosphor sheet when the stimulable phosphor sheet is exposed to the stimulating rays, is photoelectrically detected, an image signal representing the radiation image being thereby obtained. This invention particularly relates to a radiation image read-out method and apparatus, wherein a pixel density of a read-out image is capable of being altered.
2. Description of the Related Art
Radiation image recording and reproducing systems utilizing a stimulable phosphor sheet, which comprises a substrate and a layer of a stimulable phosphor overlaid on the substrate, have heretofore been widely used in practice.
With the radiation image recording and reproducing systems, a stimulable phosphor sheet is exposed to radiation carrying image information of an object, such as a human body, and a radiation image of the object is thereby recorded on the stimulable phosphor sheet. Thereafter, stimulating rays, such as a laser beam, are caused to scan the stimulable phosphor sheet in two-dimensional directions. The stimulating rays cause an exposed area of the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to the radiation. The light emitted from the exposed area of the stimulable phosphor sheet, upon stimulation thereof, is photoelectrically detected and converted into an electric image signal by photoelectric read-out means.
The image signal, which has been obtained from the radiation image recording and reproducing systems described above, is then subjected to image processing, such as gradation processing and processing in the frequency domain, such that a visible radiation image, which has good image quality and can serve as an effective tool in, particularly, the efficient and accurate diagnosis of an illness, can be obtained. The image signal having been obtained from the image processing is utilized for reproducing a visible image for diagnosis, or the like, on film or displaying a visible image for diagnosis, or the like, on a cathode ray tube (CRT) display device. In cases where the stimulable phosphor sheet, from which the image signal has been detected, is then exposed to erasing light, and energy remaining on the stimulable phosphor sheet is thereby released, the erased stimulable phosphor sheet is capable of being used again for the recording of a radiation image.
Also, a novel radiation image recording and reproducing system aiming at enhancement of a detection quantum efficiency in the formation of the radiation image, i.e., a radiation absorptivity, alight emission efficiency, an emitted light pickup efficiency, and the like, wherein a novel type of stimulable phosphor sheet is utilized, has been proposed in, for example, Japanese Patent Application No. 11(1999)-372978. With the novel type of the stimulable phosphor sheet utilized in the proposed radiation image recording and reproducing system, the radiation absorbing functions and the energy storing functions of the conventional stimulable phosphor sheet are separated from each other.
The novel type of the stimulable phosphor sheet utilized in the proposed radiation image recording and reproducing system contains a layer of a stimulable phosphor for energy storage, which is capable of absorbing light having wavelengths falling within an ultraviolet to visible region and thereby storing energy of the light having wavelengths falling within the ultraviolet to visible region, and which is capable of being stimulated by light having wavelengths falling within a visible to infrared region and thereby radiating out the stored energy as emitted light.
The novel type of the stimulable phosphor sheet should preferably take on the form combined with a layer of a phosphor for radiation absorption, which is capable of absorbing radiation and being caused to emit light having wavelengths falling within an ultraviolet to visible region. In such cases, energy from the light having wavelengths falling within the ultraviolet to visible region, which light is emitted from the layer of the phosphor for radiation absorption when the layer of the phosphor for radiation absorption is exposed to the radiation carrying image information of an object, (the amount of the energy corresponding to the radiation image information) is stored on the layer of the stimulable phosphor for energy storage. When the stimulable phosphor sheet, on which the radiation image has thus been stored, is scanned with the stimulating rays, the light carrying the radiation image information is emitted from the layer of the stimulable phosphor for energy storage.
The novel type of the stimulable phosphor sheet need not necessarily be provided with the layer of the phosphor for radiation absorption. In such cases, the novel type of the stimulable phosphor sheet is utilized in combination with a fluorescent screen, which is provided with the layer of the phosphor for radiation absorption capable of absorbing radiation and being caused to emit the light having wavelengths falling within the ultraviolet to visible region.
Specifically, in such cases, the fluorescent screen is kept in close contact with the novel type of the stimulable phosphor sheet, and the radiation carrying the image information of the object is irradiated to the fluorescent screen. As a result, the light having wavelengths falling within the ultraviolet to visible region is emitted from the layer of the phosphor for radiation absorption of the fluorescent screen. Also, energy from the light emitted from the phosphor for radiation absorption (the amount of the energy corresponding to the radiation image information) is stored on the layer of the stimulable phosphor for energy storage of the stimulable phosphor sheet. When the stimulable phosphor sheet, on which the radiation image has thus been stored, is scanned with the stimulating rays, the light carrying the radiation image information is emitted from the layer of the stimulable phosphor for energy storage.
Novel radiation image read-out apparatuses for use in the radiation image recording and reproducing systems described above have been proposed in, for example, Japanese Unexamined Patent Publication Nos. 60(1985)-111568, 60(1985)-236354, and 1(1989)-101540. In the proposed radiation image read-out apparatuses, from the point of view of keeping the emitted light detection time short, reducing the size of the apparatus, and keeping the cost low, a line sensor comprising a charge coupled device (CCD) image sensor, or the like, is utilized as the photoelectric read-out means.
Basically, the radiation image read-out apparatuses of such types comprise:
i) stimulating ray irradiating means for linearly irradiating stimulating rays onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, the stimulating rays causing the stimulable phosphor sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation,
ii) a CCD line sensor, which comprises a plurality of photoelectric conversion devices arrayed along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, and
iii) sub-scanning means for moving the stimulable phosphor sheet with respect to the stimulating ray irradiating means and the CCD line sensor and in a direction (a sub-scanning direction) intersecting with a length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays (a main scanning direction).
The stimulating ray irradiating means for linearly irradiating the stimulating rays onto the stimulable phosphor sheet in the manner described above may be constituted so as to produce fan beam-like stimulating rays. Alternatively, the stimulating ray irradiating means may be constituted so as to deflect a thin beam and to cause the deflected thin beam to linearly scan the stimulable phosphor sheet.
In cases where the radiation image is to be reproduced from the image signal, which has been obtained with the radiation image read-out apparatuses described above, it is desired that a pixel density of the reproduced image be capable of being altered in accordance with the portion of the object, the image of which was recorded, a region of interest, or the like. For example, in cases where the radiation image is an image of the chest of a human body, or the like, the pixel density of the reproduced image may be comparatively low. In cases where the radiation image is an image of bone structures, an image having a comparatively high pixel density is ordinarily required for making a diagnosis.
Heretofore, in order for the requirement for the pixel density transform to be satisfied, the pixel density of the reproduced radiation image has been altered by subjecting an analog image signal, which has been obtained with the radiation image read-out apparatuses, to analog-to-digital conversion to yield a digital image signal, and thereafter subjecting the digital image signal to pixel density transform processing.
However, in such cases, it is necessary to utilize an expensive frame memory for temporarily storing the digital image signal representing one radiation image. Therefore, the problems occur in that the cost of the radiation image read-out apparatuses cannot be kept low.
The primary object of the present invention is to provide a radiation image read-out method, wherein a pixel density of a read-out image is capable of being transformed and which is capable of being carried out with a low-cost radiation image read-out apparatus.
Another object of the present invention is to provide an apparatus for carrying out the radiation image read-out method.
The present invention provides a first radiation image read-out method, comprising the steps of:
i) linearly irradiating stimulating rays onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, with stimulating ray irradiating means, the stimulating rays causing the stimulable phosphor sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation,
ii) receiving light, which is emitted by the stimulable phosphor sheet, with a CCD line sensor comprising a plurality of photoelectric converting sections, which are arrayed along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, the received light being subjected to photoelectric conversion performed by the CCD line sensor, and
iii) moving the stimulable phosphor sheet with respect to the stimulating ray irradiating means and the CCD line sensor and in a sub-scanning direction intersecting with a length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, wherein the improvement comprises the steps of:
a) reading accumulated electric charges of the CCD line sensor, which accumulated electric charges are obtained from each set of n number of the photoelectric converting sections adjacent to one another in the array direction of the plurality of the photoelectric converting sections, where 2xe2x89xa6n, together such that the value of n is capable of being altered, the accumulated electric charges, which have thus been read together from the set of the photoelectric converting sections, being taken as an image signal component corresponding to one pixel, and
b) setting the value of n in accordance with image recording information and/or diagnostic information.
The processing for reading the accumulated electric charges together is referred to as the binning processing. The binning processing is a technique wherein, instead of the accumulated electric charge being taken out from one of the photoelectric converting sections, which are formed in the CCD line sensor, the accumulated electric charges at the plurality of the photoelectric converting sections are taken out together.
The term xe2x80x9cimage recording informationxe2x80x9d as used herein means the information giving specifics about an image recording operation, e.g., image recording conditions, such as a tube voltage of a radiation source, a tube current of the radiation source, and time over which radiation is irradiated, and conditions, such as the size of the stimulable phosphor sheet and the kind of the stimulable phosphor sheet. The term xe2x80x9cdiagnostic informationxe2x80x9d as used herein means the information concerning diagnosis utilizing the radiation image, e.g., the purpose of diagnosis, such as primary screening or close examination, and a region of interest.
The image recording information and the diagnostic information are capable of being acquired with, for example, a technique wherein the information is automatically acquired from a radiation image recording apparatus, or the like, a technique wherein the information is inputted from an identification (ID) information input device, or the like, and a technique wherein the information is transferred from an image display terminal of a medical doctor for instructing the purpose of diagnosis to a radiographic engineer.
As will be understood from the specification, it should be noted that the term xe2x80x9cmoving a stimulable phosphor sheet with respect to stimulating ray irradiating means and a CCD line sensorxe2x80x9d as used herein means movement of the stimulable phosphor sheet relative to the stimulating ray irradiating means and the CCD line sensor, and embraces the cases wherein the stimulable phosphor sheet is moved while the stimulating ray irradiating means and the CCD line sensor are kept stationary, the cases wherein the stimulating ray irradiating means and the CCD line sensor are moved while the stimulable phosphor sheet is kept stationary, and the cases wherein both the stimulable phosphor sheet and the stimulating ray irradiating means and the CCD line sensor are moved. In cases where the stimulating ray irradiating means and the CCD line sensor are moved, they should be moved together with each other.
The first radiation image read-out method in accordance with the present invention may be modified such that the method further comprises the steps of:
performing addition processing on each set of image signal components having been obtained, each of which image signal components corresponds to one of m number of read-out lines standing side by side with respect to the sub-scanning direction, where 2xe2x89xa6m, and which image signal components are adjacent to one another in the sub-scanning direction, such that the value of m is capable of being altered, a sum of the set of the image signal components, which sum has been obtained from the addition processing, being taken as one of image signal components corresponding to one line, and
setting the value of m in accordance with the image recording information and/or the diagnostic information.
Also, the first radiation image read-out method in accordance with the present invention may be modified such that the method further comprises the steps of:
altering a sub-scanning speed of the movement in the sub-scanning direction, and
setting the sub-scanning speed in accordance with the image recording information and/or the diagnostic information.
The present invention also provides a second radiation image read-out method, comprising the steps of:
i) linearly irradiating stimulating rays onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, with stimulating ray irradiating means, the stimulating rays causing the stimulable phosphor sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation,
ii) receiving light, which is emitted by the stimulable phosphor sheet, with a CCD line sensor comprising a plurality of photoelectric converting sections, which are arrayed along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays and along a sub-scanning direction intersecting with a length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, the received light being subjected to photoelectric conversion performed by the CCD line sensor, and
iii) moving the stimulable phosphor sheet with respect to the stimulating ray irradiating means and the CCD line sensor and in the sub-scanning direction intersecting with the length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays,
wherein the improvement comprises the steps of:
a) reading accumulated electric charges of the CCD line sensor, which accumulated electric charges are obtained from each set of n number of the photoelectric converting sections adjacent to one another in the array direction of the plurality of the photoelectric converting sections along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, where 2xe2x89xa6n, and m number of the photoelectric converting sections adjacent to one another in the sub-scanning direction, where 2xe2x89xa6m, together such that the value of n is capable of being altered, the accumulated electric charges, which have thus been read together from the set of the photoelectric converting sections, being taken as an image signal component corresponding to one pixel, and
b) setting the value of n and the value of m in accordance with image recording information and/or diagnostic information.
Specifically, in the second radiation image read-out method in accordance with the present invention, the binning processing is performed with respect to both the length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays (i.e, the main scanning direction) and the sub-scanning direction intersecting with the main scanning direction.
The present invention further provides a third radiation image read-out method, comprising the steps of:
i) linearly irradiating stimulating rays onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, with stimulating ray irradiating means, the stimulating rays causing the stimulable phosphor sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation,
ii) receiving light, which is emitted by the stimulable phosphor sheet, with a CCD line sensor comprising a plurality of photoelectric converting sections, which are arrayed along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, the received light being subjected to photoelectric conversion performed by the CCD line sensor, and
iii) moving the stimulable phosphor sheet with respect to the stimulating ray irradiating means and the CCD line sensor and in a sub-scanning direction intersecting with a length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays,
wherein the improvement comprises the steps of:
a) performing addition processing on each set of output signal components having been obtained from the CCD line sensor, each of which output signal components corresponds to one of m number of read-outlines standing side by side with respect to the sub-scanning direction, where 2xe2x89xa6m, and which output signal components are adjacent to one another in the sub-scanning direction, such that the value of m is capable of being altered, a sum of the set of the output signal components, which sum has been obtained from the addition processing, being taken as one of image signal components corresponding to one line, and
b) setting the value of m in accordance with image recording information and/or diagnostic information.
The present invention still further provides a fourth radiation image read-out method, comprising the steps of:
i) linearly irradiating stimulating rays onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, with stimulating ray irradiating means, the stimulating rays causing the stimulable phosphor sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation,
ii) receiving light, which is emitted by the stimulable phosphor sheet, with a CCD line sensor comprising a plurality of photoelectric converting sections, which are arrayed along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, the received light being subjected to photoelectric conversion performed by the CCD line sensor, and
iii) moving the stimulable phosphor sheet with respect to the stimulating ray irradiating means and the CCD line sensor and in a sub-scanning direction intersecting with a length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays,
wherein the improvement comprises the steps of:
a) altering a sub-scanning speed of the movement in the sub-scanning direction, and
b) setting the sub-scanning speed in accordance with image recording information and/or diagnostic information.
The present invention also provides an apparatus for carrying out the first radiation image read-out method in accordance with the present invention. Specifically, the present invention also provides a first radiation image read-out apparatus, comprising:
i) stimulating ray irradiating means for linearly irradiating stimulating rays onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, the stimulating rays causing the stimulable phosphor sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation,
ii) a CCD line sensor comprising a plurality of photoelectric converting sections, which are arrayed along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, and
iii) sub-scanning means for moving the stimulable phosphor sheet with respect to the stimulating ray irradiating means and the CCD line sensor and in a sub-scanning direction intersecting with a length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays,
wherein the improvement comprises the provision of:
a) reading means for reading accumulated electric charges of the CCD line sensor, which accumulated electric charges are obtained from each set of n number of the photoelectric converting sections adjacent to one another in the array direction of the plurality of the photoelectric converting sections, where 2xe2x89xa6n, together such that the value of n is capable of being altered, and taking the accumulated electric charges, which have thus been read together from the set of the photoelectric converting sections, as an image signal component corresponding to one pixel, and
b) control means for setting the value of n in accordance with image recording information and/or diagnostic information.
The first radiation image read-out apparatus in accordance with the present invention may be modified such that the apparatus further comprises:
signal addition processing means for performing addition processing on each set of image signal components having been obtained from the reading means, each of which image signal components corresponds to one of m number of read-out lines standing side by side with respect to the sub-scanning direction, where 2xe2x89xa6m, and which image signal components are adjacent to one another in the sub-scanning direction, such that the value of m is capable of being altered, and taking a sum of the set of the image signal components, which sum has been obtained from the addition processing, as one of image signal components corresponding to one line, and
control means for setting the value of m in accordance with the image recording information and/or the diagnostic information.
Also, the first radiation image read-out apparatus in accordance with the present invention may be modified such that the apparatus further comprises:
means for altering a sub-scanning speed of the movement in the sub-scanning direction, which movement is performed by the sub-scanning means, and
control means for setting the sub-scanning speed in accordance with the image recording information and/or the diagnostic information.
The present invention further provides an apparatus for carrying out the second radiation image read-out method in accordance with the present invention. Specifically, the present invention further provides a second radiation image read-out apparatus, comprising:
i) stimulating ray irradiating means for linearly irradiating stimulating rays onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, the stimulating rays causing the stimulable phosphor sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation,
ii) a CCD line sensor comprising a plurality of photoelectric converting sections, which are arrayed along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays and along a sub-scanning direction intersecting with a length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, and
iii) sub-scanning means for moving the stimulable phosphor sheet with respect to the stimulating ray irradiating means and the CCD line sensor and in the sub-scanning direction intersecting with the length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays,
wherein the improvement comprises the provision of:
a) reading means for reading accumulated electric charges of the CCD line sensor, which accumulated electric charges are obtained from each set of n number of the photoelectric converting sections adjacent to one another in the array direction of the plurality of the photoelectric converting sections along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, where 2xe2x89xa6n, and m number of the photoelectric converting sections adjacent to one another in the sub-scanning direction, where 2xe2x89xa6m, together such that the value of n is capable of being altered, and taking the accumulated electric charges, which have thus been read together from the set of the photoelectric converting sections, as an image signal component corresponding to one pixel, and
b) control means for setting the value of n and the value of m in accordance with image recording information and/or diagnostic information.
The present invention still further provides an apparatus for carrying out the third radiation image read-out method in accordance with the present invention. Specifically, the present invention still further provides a third radiation image read-out apparatus, comprising:
i) stimulating ray irradiating means for linearly irradiating stimulating rays onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, the stimulating rays causing the stimulable phosphor sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation,
ii) a CCD line sensor comprising a plurality of photoelectric converting sections, which are arrayed along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, and
iii) sub-scanning means for moving the stimulable phosphor sheet with respect to the stimulating ray irradiating means and the CCD line sensor and in a sub-scanning direction intersecting with a length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays,
wherein the improvement comprises the provision of:
a) signal addition processing means for performing addition processing on each set of output signal components having been obtained from the CCD line sensor, each of which output signal components corresponds to one of m number of read-out lines standing side by side with respect to the sub-scanning direction, where 2xe2x89xa6m, and which output signal components are adjacent to one another in the sub-scanning direction, such that the value of m is capable of being altered, and taking a sum of the set of the output signal components, which sum has been obtained from the addition processing, as one of image signal components corresponding to one line, and
b) control means for setting the value of m in accordance with image recording information and/or diagnostic information.
The present invention also provides an apparatus for carrying out the fourth radiation image read-out method in accordance with the present invention. Specifically, the present invention also provides a fourth radiation image read-out apparatus, comprising:
i) stimulating ray irradiating means for linearly irradiating stimulating rays onto an area of a stimulable phosphor sheet, on which a radiation image has been stored, the stimulating rays causing the stimulable phosphor sheet to emit light in proportion to an amount of energy stored thereon during its exposure to radiation,
ii) a CCD line sensor comprising a plurality of photoelectric converting sections, which are arrayed along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays, and
iii) sub-scanning means for moving the stimulable phosphor sheet with respect to the stimulating ray irradiating means and the CCD line sensor and in a sub-scanning direction intersecting with a length direction of the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays,
wherein the improvement comprises the provision of:
a) means for altering a sub-scanning speed of the movement in the sub-scanning direction, which movement is performed by the sub-scanning means, and
b) control means for setting the sub-scanning speed in accordance with image recording information and/or diagnostic information.
With the first radiation image read-out method and apparatus in accordance with the present invention, the binning processing is performed, wherein the accumulated electric charges of the CCD line sensor, which accumulated electric charges are obtained from each set of n number of the photoelectric converting sections adjacent to one another in the array direction of the plurality of the photoelectric converting sections, where 2xe2x89xa6n, are read together such that the value of n is capable of being altered. Also, the accumulated electric charges, which have thus been read together from the set of the photoelectric converting sections, are taken as an image signal component corresponding to one pixel. Therefore, the pixel density in the main scanning direction is capable of being altered arbitrarily. Specifically, for example, the accumulated electric charges of the CCD line sensor, which accumulated electric charges are obtained from each set of two photoelectric converting sections adjacent to each other in the array direction of the plurality of the photoelectric converting sections (in this case, n=2), may be read together. Also, the accumulated electric charges, which have thus been read together from each set of the two photoelectric converting sections, may be taken as an image signal component corresponding to one pixel. In such cases, the pixel density in the main scanning direction is capable of being altered to one half of the pixel density occurring when the binning processing is not performed.
Further, with the first radiation image read-out method and apparatus in accordance with the present invention, the value of n, i.e. the number of the photoelectric converting sections subjected to the binning processing with respect to the main scanning direction, is set in accordance with the image recording information and/or the diagnostic information. Therefore, the pixel density in the main scanning direction is capable of being set automatically at a value appropriate for the image recording information and/or the diagnostic information without complicated operations being required.
The first radiation image read-out method and apparatus in accordance with the present invention may be modified such that the addition processing is performed on each set of the image signal components having been obtained from the binning processing described above, each of which image signal components corresponds to one of m number of read-out lines standing side by side with respect to the sub-scanning direction, where 2xe2x89xa6m, and which image signal components are adjacent to one another in the sub-scanning direction, such that the value of m is capable of being altered, the sum of the set of the image signal components, which sum has been obtained from the addition processing, being taken as one of image signal components corresponding to one line; and the value of m is set in accordance with the image recording information and/or the diagnostic information. With the modification of the first radiation image read-out method and apparatus in accordance with the present invention, besides the pixel density in the main scanning direction being capable of being altered in the manner described above, the pixel density in the sub-scanning direction is also capable of being altered arbitrarily. Specifically, for example, the addition processing may be performed on each set of the image signal components having been obtained from the binning processing described above, each of which image signal components corresponds to one of two read-out lines standing side by side with respect to the sub-scanning direction (in this case, m=2), and which image signal components are adjacent to each other in the sub-scanning direction. Also, the sum of each set of the image signal components, which sum has been obtained from the addition processing, may be taken as one of the image signal components corresponding to one line. In such cases, the pixel density in the sub-scanning direction is capable of being altered to one half of the pixel density occurring when the addition processing is not performed.
Further, with the aforesaid modification of the first radiation image read-out method and apparatus in accordance with the present invention, the value of m, i.e. the number of the read-out lines subjected to the addition processing, is set in accordance with the image recording information and/or the diagnostic information. Therefore, the pixel density in the sub-scanning direction is capable of being set automatically at a value appropriate for the image recording information and/or the diagnostic information without complicated operations being required.
Also, the first radiation image read-out method and apparatus in accordance with the present invention may be modified such that the sub-scanning speed of the movement in the sub-scanning direction is altered, and the sub-scanning speed is set in accordance with the image recording information and/or the diagnostic information. In such cases, besides the pixel density in the main scanning direction being capable of being altered in the manner described above, the pixel density in the sub-scanning direction is also capable of being altered arbitrarily by the alteration of the sub-scanning speed. Specifically, for example, in cases where the sub-scanning speed is altered to two times as high as the original sub-scanning speed, the pixel density in the sub-scanning direction is capable of being altered to one half of the pixel density occurring when the sub-scanning speed is set at the original sub-scanning speed. Also, since the sub-scanning speed is set in accordance with the image recording information and/or the diagnostic information, the pixel density in the sub-scanning direction is capable of being set automatically at a value appropriate for the image recording information and/or the diagnostic information without complicated operations being required.
With the second radiation image read-out method and apparatus in accordance with the present invention, the binning processing with respect to the main scanning direction is performed in the same manner as that in the first radiation image read-out method and apparatus in accordance with the present invention. Therefore, the pixel density in the main scanning direction is capable of being altered arbitrarily.
Also, with the second radiation image read-out method and apparatus in accordance with the present invention, as the CCD line sensor, the CCD line sensor comprising the plurality of the photoelectric converting sections, which are arrayed along the linear area of the stimulable phosphor sheet exposed to the linear stimulating rays and along the sub-scanning direction, is employed. Further, the binning processing is performed with respect to both the main scanning direction and the sub-scanning direction. Therefore, the number of stages for reading the accumulated electric charges is capable of being kept small. Accordingly, noise is capable of being reduced, and the reading speed is capable of being kept high.
Further, with the second radiation image read-out method and apparatus in accordance with the present invention, the value of n, i.e. the number of the photoelectric converting sections subjected to the binning processing with respect to the main scanning direction, is set in accordance with the image recording information and/or the diagnostic information. Therefore, the pixel density in the main scanning direction is capable of being set automatically at a value appropriate for the image recording information and/or the diagnostic information without complicated operations being required.
Furthermore, with the second radiation image read-out method and apparatus in accordance with the present invention, the value of m, i.e. the number of the photoelectric converting sections subjected to the binning processing with respect to the sub-scanning direction, is set in accordance with the image recording information and/or the diagnostic information. Therefore, the reading speed, or the like, is capable of being set automatically at a value appropriate for the image recording information and/or the diagnostic information without complicated operations being required.
With the third radiation image read-out method and apparatus in accordance with the present invention, the addition processing is performed on each set of output signal components having been obtained from the CCD line sensor, each of which output signal components corresponds to one of m number of read-out lines standing side by side with respect to the sub-scanning direction, where 2xe2x89xa6m, and which output signal components are adjacent to one another in the sub-scanning direction. Also, the sum of each set of the output signal components, which sum has been obtained from the addition processing, is taken as one of the image signal components corresponding to one line. Therefore, the pixel density in the sub-scanning direction is capable of being altered arbitrarily. Specifically, for example, the addition processing may be performed on each set of the output signal components having been obtained from the CCD line sensor, each of which output signal components corresponds to one of two read-out lines standing side by side with respect to the sub-scanning direction (in this case, m=2), and which output signal components are adjacent to each other in the sub-scanning direction. Also, the sum of each set of the output signal components, which sum has been obtained from the addition processing, may be taken as one of the image signal components corresponding to one line. In such cases, the pixel density in the sub-scanning direction is capable of being altered to one half of the pixel density occurring when the addition processing is not performed.
Further, with the third radiation image read-out method and apparatus in accordance with the present invention, the value of m, i.e. the number of the read-out lines subjected to the addition processing, is set in accordance with the image recording information and/or the diagnostic information. Therefore, the pixel density in the sub-scanning direction is capable of being set automatically at a value appropriate for the image recording information and/or the diagnostic information without complicated operations being required.
With the fourth radiation image read-out method and apparatus in accordance with the present invention, the sub-scanning speed of the movement in the sub-scanning direction is altered. By the alteration of the sub-scanning speed, the pixel density in the sub-scanning direction is capable of being altered arbitrarily. Specifically, for example, in cases where the sub-scanning speed is altered to two times as high as the original sub-scanning speed, the pixel density in the sub-scanning direction is capable of being altered to one half of the pixel density occurring when the sub-scanning speed is set at the original sub-scanning speed.
Also, with the fourth radiation image read-out method and apparatus in accordance with the present invention, the sub-scanning speed is set in accordance with the image recording information and/or the diagnostic information. Therefore, the pixel density in the sub-scanning direction is capable of being set automatically at a value appropriate for the image recording information and/or the diagnostic information without complicated operations being required.
Further, with the first, second, third, and fourth radiation image read-out methods in accordance with the present invention and the first, second, third, and fourth radiation image read-out apparatuses in accordance with the present invention, the pixel density is altered at the stage at which an analog image signal is formed. Therefore, an expensive frame memory for temporarily storing a digital image signal representing one radiation image need not be utilized. Accordingly, the cost of the radiation image read-out apparatuses is capable of being kept low.